The present invention is directed to structural systems comprised of reinforced resin members which are mechanically interlocked together. Such systems are often used to construct gratings used as a floor or walkway, but may be used to construct other structural components such as walls, stairs, shelving, and the like.
FIGS. 13A, 13B and 13C are a top view, front view, and side view, respectively, of a three-part, prior art system that consists of a load bearing bar 101, a notched bar 102, (seen best in FIG. 14) and a locking groove rod 103, (seen best in FIG. 15). The three-part system requires pultrusion of three shapes, the load bearing bars 101, notched bars 102, and locking groove rods 103. Furthermore, after pultrusion, the bearing bars 101 must be fabricated to provide through holes (104 in FIG. 13C) and the notched bars 102 must be fabricated to provide notches (105 in FIG. 14) for spacing of the bearing bars 101. Once fabricated, the three-part system is assembled by inserting the notched bar 102 into parallel positioned bearing bars 101 through holes 104. Thereafter, the locking groove rod 103, having a groove 106 (best seen in FIG. 15) is inserted into holes 104 with the groove 106 receiving a base of the notched bar 102 to force the notched bar 102 into engagement with the load bearing bars 101. After the three-part system in FIG. 13A is assembled, it is placed on a slanted table and a low viscosity epoxy adhesive is applied around the intersection of the notched bars 102 and the bearing bars 101. That procedure is performed twice at two different angles to complete the assembly. When the assembly is used for flooring, a surface grit (not shown), which may consist of silica sand in a vinyl ester or epoxy resin, is applied to a top surface of the assembly. The assembly is allowed to cure for a period of several hours before the process is considered complete. The prior art procedure is labor intensive and requires multiple steps. It also presents significant lead-time from order to completion and delivery of the assembly. Furthermore, the prepositioning of holes 104 prohibits the repositioning of the notched bars 102 to those areas where additional strength may be needed. A significant issue with respect to the prior art designs that require drilling through the I-bar web is the reduction of mechanical strength which occurs when the fiber reinforcement is interrupted.
In one such design, the location of the holes 104 is near the upper surface of the completed assembly such that the notched bars 102 are flush with the top of the bearing bars 101. The geometry of those components places the bottom of the hole 104 very near the center of the load bearing bars 101, which is where the highest shear stress is located during flexural loading. The tendency to split along the centerline between fabricated holes requires the use of reinforced mats to increase cross-directional strength. In the case of extreme fire exposure tests, one failure mode is for the load bearing bars to fracture into segments equal to the length of the bearing bar between the holes 104. Elimination of the holes 104 would increase the load bearing capacity of the bearing bars 101 substantially while reducing or eliminating the need for expensive cross-directional reinforcement materials.
A two-component, fiberglass reinforced, molded resin grating is disclosed in U.S. Pat. No. 4,760,680. The grating is formed of first and second sets of mutually parallel, interlocking, fiberglass reinforced, molded resin bars with the sets extending transversely to one another. One set consists of bearing bars of rectangular cross-section including at longitudinally-spaced positions within an upper edge, an inverted U-shaped notch including oppositely-directed, downwardly and outwardly oblique slots terminating at their upper ends adjacent the upper edge of the bearing bars in upwardly and outwardly diverging oblique cam surfaces. The second set of bars consists of cross bars of inverted U-shaped cross section including a horizontal base portion and a pair of downwardly and outwardly diverging legs of a thickness equal to the width of the diverging slots and being respectively received in the slots. The legs of the cross bars at longitudinally spaced positions are provided with rectangular locking notches from the free ends upwardly of a width generally equal to the thickness of the bearing bars and of a height which is less than the vertical height of the cross bars. The cross bars are forced downwardly at the locking notches into the inverted U-shaped notches formed within the upper edge of the bearing bars with the cam surfaces deflecting the oblique legs of the cross bar to momentarily deform the legs to cause the portions of the legs at the locking notches to snap into the oblique slots of the inverted U-shaped notches within the bearing bars to mechanically interlock the first and second sets of bars together. In this two-piece system, both members have notches formed therein.
The need exists for a structural system comprised of interlocking mechanical components which does not require any notching or holes to be formed in the load-bearing component. Furthermore, the components must be designed to enable cost-effective fabrication. There should ideally be a minimal number of components and a simple method of assembling the components that can be automated.
The present invention is directed to a structural system comprised of two components. The first component is an I-shaped bearing member having an upper flange and a lower flange connected by a web. The upper and lower flanges have undercuts formed therein. The second component is a connection member having a notch in each corner for engaging with the undercuts in the upper and lower flanges. The components of this system may be used to construct a structural component comprising a plurality of I-shaped bearing members positioned parallel to one another. A plurality of connection members interconnect the bearing members; the two upper notches of the connection member engage the undercuts in the upper flanges of two adjacent bearing members while the two lower notches engage the undercuts in the lower flanges of two adjacent bearing members.
The present invention is also directed to a method of constructing a structural component comprising positioning a plurality of bearing members parallel to one another. A plurality of connection members having cam surfaces are inserted between adjacent bearing members. Each connection member is rotated to first bring the cam surface into contact with the adjacent bearing members and then to lock the connection member in place.
The present invention provides several advantages over, for example, the three-part prior art system. The present invention eliminates the logistics of molding three pultrusion shapes and controlling associated inventory levels. A structural component, such as a floor grating, wall panel, shelf, etc., can be assembled with fewer fabrication steps. Because the connection members can be located where desired, new spacing patterns can be employed to optimize load distribution rather than the uniform pattern dictated by the three-part prior art system. When a structural component is assembled with the present invention, adjacent components can be easily connected with connection members, because each component has at its outside edge one side of a bearing bar. That facilitates field installation in which one structural component may be secured to another resulting in a functional, seamless system, such as a flooring system. Use of connection members with specialized features allows for other objects to be connected to, carried by, or embedded in the structural component. By creating a molded surface texture on the connection members, and by applying a surface grit in-line during pultrusion of the bearing bar, the potential exists to assemble a flooring product in a very cost-effective manner. Those, and other advantages and benefits, will be apparent from the Description of the Preferred Embodiments appearing herein below.